Experimental study on electrically heated catalyst coupling strategies for ultra-low emissions and energy-efficient thermal management in diesel engines

To address increasingly stringent emission regulations, advanced thermal management technologies such as Electrically Heated Catalysts (EHCs) have shown significant potential for improving cold-start emission control in diesel engines. However, systematic investigations into the combined effects of EHC coupling configurations and activation strategies on the control of NOx, NH₃, and N₂O emissions under both cold and hot conditions remain limited. In this study, two EHC coupling configurations—front-mounted and rear-mounted—were established and evaluated under both cold and hot World Harmonized Transient Cycle (WHTC) conditions, with varying EHC activation durations (60 s and 480 s). The impacts of EHC layout and heating duration on exhaust temperature profiles and emission performance were comprehensively analyzed. Results indicate that, under cold WHTC, long-duration heating (480 s) with a front-mounted EHC substantially increases catalyst temperatures, shortens urea injection delay, and significantly enhances the catalytic conversion of CO and NOx. Notably, the specific NOx emissions were reduced to as low as 138.58 mg/kWh, meeting and even outperforming the Euro 7 limits. Additionally, notable reductions in N₂O and NH₃ emissions were observed. Under hot WHTC conditions, short-duration heating (60 s) was found sufficient to rapidly activate the aftertreatment system. Furthermore, energy efficiency analysis revealed that short-duration EHC activation achieved higher emission reduction benefits per unit of energy consumed, particularly for CO and NOx control during cold starts. This study underscores the crucial role of EHCs in cold-start emission reduction and provides both theoretical insights and experimental evidence to inform the development of energy-efficient and low-emission strategies for future diesel engine aftertreatment systems.